add twitter accounts

[mohit2152sharma]

Just as a suggestion, not sure if it is worth adding as a separate section, but there are couple of twitter accounts which are worth following from a beginner's perspective as they post regular content. For example:

1. R posts you might have missed
2. #RStats question a day
3. R function a day
4. Rstats

(full disclosure: I manage the account #RStats question a day)

[oscarbaruffa]

thanks! I think a better place will be to add them in the t4rstats.com book, which I'll do :)